Modified atmosphere storage is to place the fruits and vegetables in a relatively closed environment. By adjusting the concentration of gas around the fruits and vegetables to control their respiration effectively, the purpose of delaying the deterioration of fruits and vegetables or regulating the ripening of fruits can be achieved. According to statistics, the decay rate of fruits and vegetables due to improper storage reaches 20%-30% annually, which ranks first in the world and results in economic losses of up to 75 billion RMB. Only 20% of the total output of fruits and vegetables in China are stored after being harvested, and the fruits and vegetables stored with modified atmosphere are less than 1% of the total output, which is far from the average post-harvest storage percentage of 80% in developed countries.
Gases are usually stored and transported in high-pressure-resistant steel cylinders, but there is a risk of leakage and explosion during use. The adsorption of gas into solid matrices can avoid such defects effectively, wherein the gas physically captured in solid matrices has characteristics such as slow release, which is an important application if small amount and continuous possession are necessary. For example, in the storage and transportation process after harvesting bananas or apples, the solid powder matrices adsorbing with ethylene gas can be placed in a warehouse or transport vehicle so that the slowly released ethylene gas can ripen the fruit in a period of time to regulate the ripening time of fruits.
Ethylene is an important gas for regulation of plant maturation, which is known as “plant hormone” and can accelerate fruit ripening or promote seed germination (such as mung bean). In the field of vegetable and fruit preservation, ethephon is widely used to induce the release of ethylene from plants or fruits, but it is to some extent toxic, whose safety has attracted much attention.
At present, the adsorption of ethylene gas by cyclodextrin has been reported, and the preparation method is mostly liquid phase method. A saturated solution is prepared from cyclodextrin powder and placed in a high-pressure reactor. Then ethylene is introduced and the reaction begins at 25° C. for 120 h. After washing and drying, cyclodextrin sample adsorbing with ethylene is obtained. The recovery rate of the sample is 15% to 40%, and the adsorption rate of ethylene is 2.3% to 2.8% (Ho, B T, Joyce, D C, Bhandari, B R (2011), Encapsulation of ethylene gas into α-cyclodextrin and characterization of the inclusion complex, Food Chemistry, 127, 572-580). However, cyclodextrin used in the method is expensive, the adsorption process is complicated with a low sample recovery rate and ethylene adsorption rate, which makes it not suitable for large-scale production in food industry.